Then, 100 mL bacterial
cell suspensions were placed in each well/plate. Microplates
were incubated for 24 h at 37 C. The lowest concentrations
without visible growth completely inhibited the bacteria (MICs).
Dimethyl sulfoxide was used as a control and Mueller–Hinton
broth as negative control. Tetracycline and vancomycin were
used as positive controls for MRSA, while cefotaxime and
meropenem were used as positive controls for ESBL–producing
bacteria and CRE. The assay was repeated twice with three
replicates per assay.